1. Field of the Invention
The present invention relates to a method, an apparatus, and a program for data management by relating data.
2. Description of the Related Art
Various data management methods by relating data have been proposed. For example, master content and subordinate content may be determined so that a change in the master content can be reflected in the subordinate content. Furthermore, a system has been proposed for managing various content (U.S. Pat. No. 6,192,191). In this method, a management file stores information on a relationship among the content and the relationship can be known by referring to the management file.
Meanwhile, data (content) stored in a hard disc or the like of a computer are subjected to various kinds of processing carried out by a user, such as copying, manipulation, and image processing in the case of image data. Therefore, data sets generated from an original data set (hereinafter referred to as derivative data sets for distinction from the original data set) exist in many cases in one computer. When a user wishes to carry out some kind of processing on one of the data sets, the user needs to know a relationship between the data set and the other data sets. For example, in the case where the user wishes to delete one of the data sets, the user does not need to be anxious about deleting the data set if the user knows that the original data set of the data set to be deleted is stored. Furthermore, in the case where the user wishes to carry out processing that requires time and specialized knowledge (such as image processing on an image data set), if the user knows that a data set having been subjected to the same processing exists, the user simply uses the data set to save his/her time. In other words, clarifying the relationship between the original data set and the derivative data sets improves security and convenience for the user upon management of the data sets.
However, in the data management method using the relationship between master content and subordinate content described above, an original data set is lost although the change in the master content can be reflected in the subordinate content and integrity among the content can be maintained. For example, if one of image data sets as the master content is subjected to color conversion processing, image data sets as the subordinate content can also be subjected to the color conversion processing, and the original data set is changed. Therefore, if another type of image processing such as gradation conversion processing or density conversion processing needs to be carried out on the original data set, the desired data set cannot be obtained, since the original data set has been lost due to the color conversion processing. In order to solve this problem, in the case where a user needs to carry out processing on master content, the user needs to copy an original data set to be stored, which is troublesome for the user. Moreover, in the case where subordinate content is subjected to some kind of processing, a change caused by the processing is not reflected in master content. Therefore, a state of the subordinate content is not known when the master content is referred to. Consequently, a user needs to memorize which content is master or subordinate, which is also troublesome.
In the case where the management file is used for managing the relationship among the content, if a user wishes to carry out some kind of processing thereon, the user needs to refer to the management file, which is inconvenient. Furthermore, since the management file is dependent on a system, management of the content can only be carried out in one system in this method. Therefore, although a relationship among content stored in one computer can be managed, if a portion of the content is copied and stored in another computer, the computer storing the copied content cannot trace back the original content by using the copied content.